Climate change traditionally refers to the constant, natural fluctuations in Earth’s climate, however recently has become the common term for the man-made, rapid changes happening since the Industrial Revolution. Other names include ‘global warming’, ‘the climate crisis’ and ‘the climate emergency’. Due to human activities - like burning fossil fuels - an excess of greenhouse gases accumulated in the air over time trapping heat in the atmosphere resulting in an overall warming effect. This increasing average temperature provokes severe changes in the climate as we know it.
The greenhouse effect is a natural phenomena in which the greenhouse gases in the atmosphere trap heat leading to an increased temperature. As mankind is increasing the amount of greenhouse gases in air, the greenhouse effect is intensified resulting in an unnatural, rapid rise in temperature changing the climate as we know it - anthropogenic (man-made) climate change.
Energy emitted by our sun comes in the form of ultraviolet, visible and near-infrared radiation of which a part radiates towards Earth. The part of this radiation, which is not reflected back to space, penetrates the atmosphere unimpeded and is absorbed by Earth’s surface. Earth itself, as all bodies, emits the same amount of radiation it absorbs - keeping it’s equilibrium temperature. As the Earth’s surface is colder than the suns’, it emits a different type of radiation - a lower energy one with longer wavelengths - infrared radiation. Radiative active gases in the atmosphere - greenhouse gases - absorb this infrared radiation and emit it in all directions. Parts of it fall back on to Earth’s surface. Because of that, Earth receives twice as much radiation from the atmosphere as it does from the sun resulting in a higher temperature - this is referred to as the greenhouse effect.
This term refers to the total amount of carbon dioxide produced by a person, organization, or activity during a given period of time. The carbon footprint can also consider other greenhouse gases produced, such as methane, nitrous oxide, and chlorofluorocarbons.
It’s a useful measurement to monitor how much carbon dioxide and other greenhouse gas emissions are produced by a person, organization, or activity. It can be expressed by tons of CO2 or CO2-equivalent gases emitted per year.
Carbon offsetting1 is the action of reducing, avoiding or sequestering a unit of carbon dioxide or other greenhouse gases to compensate for emissions occurring somewhere else. Carbon offsetting is frequently done by purchasing carbon credits, but it can also be done by funding practices that actively remove carbon dioxide from the atmosphere. Carbon offset schemes allow companies and individuals to compensate for their carbon footprint, it’s a way to balance out their emissions or reduce the damage caused by a specific activity, such as traveling by plane.
According to the FAO2, a carbon credit is a currency for trading carbon emissions in the carbon market. A carbon credit represents the right of an entity to release one ton of carbon dioxide or the equivalent amount of other greenhouse gases into the atmosphere. However, carbon credits have some limitations since the entity would be paying someone else to prevent a negative impact instead of actually removing carbon dioxide from the atmosphere. For example, if an entity emits two billion tonnes of CO2, it can purchase carbon credits to ensure that another entity reduces two billion tonnes of CO2 from its own emissions. Carbon Neutrality Carbon neutrality refers to a balance between the amount of CO2 emissions produced by an entity or individual and the amount of CO2 it pays to remove from the atmosphere or reduce somewhere else. For example, if a company produces two billion tons of CO2 and purchases carbon credits to compensate for the exact amount of CO2 produced or funds other carbon offset schemes to actively remove two billion tons of CO2 from the atmosphere, then it is considered to be carbon neutral.
As defined by the UNEP1, carbon sequestration is the action of removing carbon from the atmosphere and depositing it in other carbon sinks, such as forests or the ocean. These reservoirs store carbon dioxide for a long time and prevent it from entering the Earth’s atmosphere. For instance, forest regrowth is a form of carbon sequestration. Trees will remove carbon dioxide from the atmosphere through photosynthesis and use it to build wood, leaves, and roots. Therefore, they could store carbon for a long time.
Carbon removal, carbon dioxide removal or CDR, refers to a group of anthropogenic activities that actively remove and sequester carbon dioxide from the atmosphere, according to the UNEP1. Carbon removal uses natural-based, technology-based, and combined natural/technology-based practices to create negative emissions. Even though carbon removal is essential to remove greenhouse gases already in the atmosphere, it isn’t a substitute for reducing carbon dioxide emissions and deforestation. Carbon removal practices and technologies include reforestation, afforestation, carbon farming, direct air capture and storage, enhanced weathering, and others.
Negative emissions are the opposite of releasing greenhouse gases. According to the IPCC3, negative emissions refer to the deliberate removal of carbon dioxide from the atmosphere via carbon removal practices and technologies. For some greenhouse gas-emitting activities like aviation, it’s impossible to get their emissions down to zero. Therefore, the best alternative for some entities is to combine reduction efforts with negative emissions to balance out their emissions.
According to the IPCC3, net-zero means that anthropogenic emissions are balanced by removing an equivalent amount of carbon dioxide from the atmosphere over a specified period. Unlike carbon neutrality, entities can only achieve net-zero via carbon removal practices and technologies. However, to get to net-zero, it’s also important to dramatically reduce greenhouse gas emissions by replacing greenhouse gas-emitting technologies with clean ones. With this approach, the remaining greenhouse gas emissions could be balanced with carbon removal options to reach net-zero.
Climate positive or carbon negative means that an entity or activity removes more carbon dioxide from the atmosphere than it emits. In other words, it produces a positive impact that counteracts climate change. To become climate positive, an entity shouldn’t rely on carbon offsets to delay reductions of its emissions. Carbon offsets should only be used in addition to other reduction efforts to reach the climate positive goal. For example, if a company produces two billion tons of CO2e per year but removes three billion tons of CO2e per year, it’s climate positive.